The present invention relates, in general, to image acquisition and specifically to X-ray image acquisition.
X-ray imaging is widely used in various fields of life. For example, X-ray imaging has been a standard medical diagnostic tool for decades. A typical X-ray image acquisition apparatus suitable for low energy X-rays includes a phosphor X-ray conversion screen and a photo detector array aligned with each other. The phosphor conversion screen generates optical light photons in response to the X-ray radiation. The optical light photons are transmitted to the photo detector array under the conversion screen. The photo detector array generates electric signals in response to the optical light photons. Electronics circuitry coupled to the photo detector array processes the electric signals and generate images. A typical high energy X-ray image acquisition apparatus includes a copper screen and a Gadolinium Oxysulfide panel over a photo detector array. The high energy X-ray radiation passes through the copper screen, which absorbs a portion of the X-ray radiation and generates energetic electrons. The electrons pass into the Gadolinium Oxysulfide panel and generate optical light photons. Another portion of the X-ray radiation passes through the copper screen and interacts with Gadolinium Oxysulfide to produce optical light photons. The photo detector array senses the optical light photons and generates electric signals in response thereto.
Different applications require images acquired using X-ray radiation at different energy levels. For example in the field of medical diagnostic procedures, low energy xe2x80x9cdiagnosticxe2x80x9d X-ray images are generally used in soft tissue diagnostics, and high energy X-rays are used for treatment in radiation oncology and imaging are produced with imaging systems in conjunction with the treatment. The quality of the acquired image depends on the image acquisition procedures and the equipment used.
X-ray images at different energy levels are presently created using different image acquisition apparatuses as described above. Maintaining multiple sets of X-ray image apparatuses will increase the operating and overhead costs for a medical diagnostic facility. It will also affect the efficiency of the facility by increasing the idle time of the apparatuses. These effects are exacerbated further for those facilities with relatively small patient bases.
Accordingly, it would be advantageous to have an apparatus that is capable of forming X-ray images with X-rays at different energy levels. It is desirable for the apparatus to be simple and reliable. It is also desirable if the apparatus can be used on an existing X-ray imaging system. It would be of further advantage to be able to optimize the image quality for its intended use.
A primary benefit of the present invention is providing an apparatus capable of forming X-ray images with X-rays at different energy levels. A particular benefit of some embodiments of the present invention is providing the apparatus that is simple and reliable. A specific benefit of some embodiments of the present invention is providing the apparatus that can be used on existing X-ray imaging systems. An additional benefit in accordance with some embodiments of the present invention is providing the apparatus that is capable of optimizing the image quality for its intended use.
In order to achieve these and other objectives of the present invention, an X-ray image acquisition apparatus includes an X-ray conversion panel aligned with a photo detector array. The X-ray conversion panel generates optical light photons in response to the X-ray radiation of different energy levels. The photo detector array generates electric signals in response to the optical light photon received from the X-ray conversion panel.
In accordance with an embodiment of the present invention, the conversion panel is made up of a plurality of X-ray conversion cells arranged in a two-dimensional array. Each conversion cell has a conversion body in its core. The conversion body is made of a scintillating material, e.g., Cesium Iodine, Bismuth Germanate, Cadmium Tungstate, etc., that generates optical light photons in response to X-ray radiation illuminating thereon and is substantially transparent to the generated optical light photons. The conversion bodies are preferably sufficiently long to absorb the X-ray radiation over a wide range of energy levels. Light reflective films are attached to the sidewalls of the conversion bodies to collimate the optical light photons generated in the conversion bodies. The cross section areas of the conversion bodies are preferably sufficiently small to provide a satisfactory spatial resolution of the X-ray image generated using the conversion panel. In a preferred embodiment, the top of each conversion body is covered with an X-ray transparent and light reflective film. This film reflects those optical light photons generated in the conversion bodies and propagating away from the photo detector array, thereby increasing the efficiency of the conversion panel.
In accordance with an embodiment, the photo detector array includes an array of photo detectors aligned with the conversion cells in the conversion panel and generating electric signals in response to the optical light photons received from the corresponding conversion cells in the conversion panel. Electronics circuits coupled to the photo detector array process the electric signals and generate the images.